1. Field of Invention
The invention relates to an outer shell structure and, in particular, to a combining structure for the decorating shell of a ceiling fan.
2. Related Art
As shown in FIG. 8, the decorating cover for the hanging bell of a conventional ceiling fan. The surrounding surface at the bottom of the hanging bell 61 is formed with several through holes 62. Several screws go through the through holes 62 to fix the hanging bell 61 under a hanging frame (not shown). Since the screws are exposed at the bottom of the hanging bell 61, it is customary to cover them with a decorating cover 63. The bottom of the hanging bell 61 converges downward to form a neck 64. The inner rim of the neck 64 is protruded toward its center with at least three urging parts 65. The inner rim of the decorating cover 63 is protruded upward with catching parts 66 corresponding to the urging parts 65. Each of the catching parts 66 is formed with a groove 67. To assemble them, as shown in FIG. 9, one only needs to align the urging parts 65 with the concave part between the catching parts, followed by rotating the decorating cover 63 so that the urging parts 65 go into the grooves 67 of the catching parts 66. This completes the assembly.
However, due to the cost constraint, the precision between the urging parts 65 and the grooves 67 is not good enough. When the space of the groove 67 is greater than the thickness of the urging part 65, there will be collisions between them when the ceiling fan is in operation. It has the drawbacks of noises and instability. If the space of the groove 67 is smaller than the thickness of the urging part 65, the drawback is that the urging parts 65 cannot be rotated into the grooves 67.